Teach find_(library|package) about Linux multiarch (#12037)

Implement support for multiarch as specified here:

  http://wiki.debian.org/Multiarch
  https://wiki.ubuntu.com/MultiarchSpec

Detect the <arch> part of <prefix>/lib/<arch> from the implicit library
search path from each compiler to set CMAKE_<lang>_LIBRARY_ARCHITECTURE.
Define CMAKE_LIBRARY_ARCHITECTURE using one of these values (they should
all be the same).  Teach the find_library and find_package commands to
search <prefix>/lib/<arch> whenever they would search <prefix>/lib.

5 files changed, 29 insertions, 0 deletions

diff --git a/Modules/CMakeCCompiler.cmake.in b/Modules/CMakeCCompiler.cmake.in
index 051df4c..04a5cec 100644
--- a/Modules/CMakeCCompiler.cmake.in
+++ b/Modules/CMakeCCompiler.cmake.in
@@ -28,6 +28,7 @@ SET(CMAKE_C_LINKER_PREFERENCE 10)
 # Save compiler ABI information.
 SET(CMAKE_C_SIZEOF_DATA_PTR "@CMAKE_C_SIZEOF_DATA_PTR@")
 SET(CMAKE_C_COMPILER_ABI "@CMAKE_C_COMPILER_ABI@")
+SET(CMAKE_C_LIBRARY_ARCHITECTURE "@CMAKE_C_LIBRARY_ARCHITECTURE@")
 
 IF(CMAKE_C_SIZEOF_DATA_PTR)
   SET(CMAKE_SIZEOF_VOID_P "${CMAKE_C_SIZEOF_DATA_PTR}")
@@ -37,6 +38,10 @@ IF(CMAKE_C_COMPILER_ABI)
   SET(CMAKE_INTERNAL_PLATFORM_ABI "${CMAKE_C_COMPILER_ABI}")
 ENDIF(CMAKE_C_COMPILER_ABI)
 
+IF(CMAKE_C_LIBRARY_ARCHITECTURE)
+  SET(CMAKE_LIBRARY_ARCHITECTURE "@CMAKE_C_LIBRARY_ARCHITECTURE@")
+ENDIF()
+
 SET(CMAKE_C_HAS_ISYSROOT "@CMAKE_C_HAS_ISYSROOT@")
 @CMAKE_C_OSX_DEPLOYMENT_TARGET_FLAG_CODE@
 
diff --git a/Modules/CMakeCXXCompiler.cmake.in b/Modules/CMakeCXXCompiler.cmake.in
index d7ae8d9..ea06526 100644
--- a/Modules/CMakeCXXCompiler.cmake.in
+++ b/Modules/CMakeCXXCompiler.cmake.in
@@ -29,6 +29,7 @@ SET(CMAKE_CXX_LINKER_PREFERENCE_PROPAGATES 1)
 # Save compiler ABI information.
 SET(CMAKE_CXX_SIZEOF_DATA_PTR "@CMAKE_CXX_SIZEOF_DATA_PTR@")
 SET(CMAKE_CXX_COMPILER_ABI "@CMAKE_CXX_COMPILER_ABI@")
+SET(CMAKE_CXX_LIBRARY_ARCHITECTURE "@CMAKE_CXX_LIBRARY_ARCHITECTURE@")
 
 IF(CMAKE_CXX_SIZEOF_DATA_PTR)
   SET(CMAKE_SIZEOF_VOID_P "${CMAKE_CXX_SIZEOF_DATA_PTR}")
@@ -38,6 +39,10 @@ IF(CMAKE_CXX_COMPILER_ABI)
   SET(CMAKE_INTERNAL_PLATFORM_ABI "${CMAKE_CXX_COMPILER_ABI}")
 ENDIF(CMAKE_CXX_COMPILER_ABI)
 
+IF(CMAKE_CXX_LIBRARY_ARCHITECTURE)
+  SET(CMAKE_LIBRARY_ARCHITECTURE "@CMAKE_CXX_LIBRARY_ARCHITECTURE@")
+ENDIF()
+
 SET(CMAKE_CXX_HAS_ISYSROOT "@CMAKE_CXX_HAS_ISYSROOT@")
 @CMAKE_CXX_OSX_DEPLOYMENT_TARGET_FLAG_CODE@
 
diff --git a/Modules/CMakeDetermineCompilerABI.cmake b/Modules/CMakeDetermineCompilerABI.cmake
index 7f918e6..39d1f17 100644
--- a/Modules/CMakeDetermineCompilerABI.cmake
+++ b/Modules/CMakeDetermineCompilerABI.cmake
@@ -86,6 +86,17 @@ FUNCTION(CMAKE_DETERMINE_COMPILER_ABI lang src)
       SET(CMAKE_${lang}_IMPLICIT_LINK_LIBRARIES "${implicit_libs}" PARENT_SCOPE)
       SET(CMAKE_${lang}_IMPLICIT_LINK_DIRECTORIES "${implicit_dirs}" PARENT_SCOPE)
 
+      # Detect library architecture directory name.
+      IF(CMAKE_LIBRARY_ARCHITECTURE_REGEX)
+        FOREACH(dir ${implicit_dirs})
+          IF("${dir}" MATCHES "/lib/${CMAKE_LIBRARY_ARCHITECTURE_REGEX}$")
+            GET_FILENAME_COMPONENT(arch "${dir}" NAME)
+            SET(CMAKE_${lang}_LIBRARY_ARCHITECTURE "${arch}" PARENT_SCOPE)
+            BREAK()
+          ENDIF()
+        ENDFOREACH()
+      ENDIF()
+
     ELSE(CMAKE_DETERMINE_${lang}_ABI_COMPILED)
       MESSAGE(STATUS "Detecting ${lang} compiler ABI info - failed")
       FILE(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
diff --git a/Modules/CMakeFortranCompiler.cmake.in b/Modules/CMakeFortranCompiler.cmake.in
index 146a6f2..53d9552 100644
--- a/Modules/CMakeFortranCompiler.cmake.in
+++ b/Modules/CMakeFortranCompiler.cmake.in
@@ -34,6 +34,7 @@ ENDIF(UNIX)
 # Save compiler ABI information.
 SET(CMAKE_Fortran_SIZEOF_DATA_PTR "@CMAKE_Fortran_SIZEOF_DATA_PTR@")
 SET(CMAKE_Fortran_COMPILER_ABI "@CMAKE_Fortran_COMPILER_ABI@")
+SET(CMAKE_Fortran_LIBRARY_ARCHITECTURE "@CMAKE_Fortran_LIBRARY_ARCHITECTURE@")
 
 IF(CMAKE_Fortran_SIZEOF_DATA_PTR AND NOT CMAKE_SIZEOF_VOID_P)
   SET(CMAKE_SIZEOF_VOID_P "${CMAKE_Fortran_SIZEOF_DATA_PTR}")
@@ -43,5 +44,9 @@ IF(CMAKE_Fortran_COMPILER_ABI)
   SET(CMAKE_INTERNAL_PLATFORM_ABI "${CMAKE_Fortran_COMPILER_ABI}")
 ENDIF(CMAKE_Fortran_COMPILER_ABI)
 
+IF(CMAKE_Fortran_LIBRARY_ARCHITECTURE)
+  SET(CMAKE_LIBRARY_ARCHITECTURE "@CMAKE_Fortran_LIBRARY_ARCHITECTURE@")
+ENDIF()
+
 SET(CMAKE_Fortran_IMPLICIT_LINK_LIBRARIES "@CMAKE_Fortran_IMPLICIT_LINK_LIBRARIES@")
 SET(CMAKE_Fortran_IMPLICIT_LINK_DIRECTORIES "@CMAKE_Fortran_IMPLICIT_LINK_DIRECTORIES@")
diff --git a/Modules/Platform/Linux.cmake b/Modules/Platform/Linux.cmake
index 6490dd1..57d1b34 100644
--- a/Modules/Platform/Linux.cmake
+++ b/Modules/Platform/Linux.cmake
@@ -45,6 +45,9 @@ ELSE(DEFINED CMAKE_INSTALL_SO_NO_EXE)
   ENDIF(EXISTS "/etc/debian_version")
 ENDIF(DEFINED CMAKE_INSTALL_SO_NO_EXE)
 
+# Match multiarch library directory names.
+SET(CMAKE_LIBRARY_ARCHITECTURE_REGEX "[a-z0-9_]+-linux-gnu")
+
 INCLUDE(Platform/UnixPaths)
 
 # Debian has lib64 paths only for compatibility so they should not be